1. Field Of The Invention
The present invention relates to a lens mounting apparatus for mounting a television camera.
2. Description Of The Prior Art
In a conventional television camera, especially a television camera for closed-circuit televisions (CCTVs), an image pickup element is axially movably mounted with respect to a lens holder for mounting the lens so that the image pickup element can be flange-back-adjusted (adjusted in the direction of the optical axis of the image pickup element) from the front of the camera.
FIG. 6 shows a conventional lens mounting apparatus, in which an image pickup element 53 is held by a sensor mount 54 and a holder 55. A leaf spring 56 is vertically mounted at the front side of a bracket member 52 by means of a screw bolt 60. The image pickup element 53, the sensor mount 54 and the holder 55 assembled as above-mentioned, are mounted to the rear of the bracket member 52 by means of screws 61. The bracket member 52 is fitted inside of the rear of the lens holder 51 which is mounted to the front chassis 59 by screw bolts 62, the front escutcheon 58 is mounted to the front chassis 59, and a front projection of the lens holder 51 projects frontward through a bore 63 at the front escutcheon 58. An adjusting ring 57 screws with a screw thread at the outer periphery of the projection.
The adjusting ring 57 is rotated to push at the rear end thereof the bracket member 52, thereby enabling the bracket member 52 and the image pickup element 53 to be moved longitudinally. After the movable adjustment finishes, a fixing screw 65 screws with a threaded bore formed at the adjusting ring 57 and the tip of the fixing screw 65 is brought into press-contact with the screw thread 64 at the lens holder 51, thereby locking it.
The adjusting ring 57 is rotated to adjust a flange back distance, (distance from the lens holder surface to the image formation face) of the image pickup element 53, thereby enabling variation in the flange back distance of lens to be absorbed.
In recent years, television camera for CCTVs have used a variety of different television lenses in a flange back distance so that in addition to the socalled C mount lens (having a flange back distance of 17.526 mm), it is required that the camera is provided with lenses of a different flange back distance (for example, the flange back distance being 12.5 mm). The above-mentioned conventional construction, however, can adjust variation in the flange back distance, but cannot be provided with the lenses different in the flange back distance, thereby creating the problem in that only a defined lens is usable therein.